Inorganic fiber composite thermal insulation material and preparation method thereof

Abstract

The present invention relates to the field of thermal insulation materials, and discloses an inorganic fiber composite thermal insulation material and a preparation method thereof. The composite thermal insulation material comprises: a sheet-like matrix formed by flocculation and entanglement of inorganic fibers; and an inorganic filler and a modified thermal insulation filler (polyacrylic acid modified multimetallic compound) dispersed in the matrix. The composite thermal insulation material of the present invention contains polyacrylic acid modified multimetallic compounds. On the one hand, the mutual doping of multimetallic compounds can reduce the thermal conductivity of the material; on the other hand, during the material molding process, polyacrylic acid can promote the appropriate degree of flocculation of inorganic fibers, thereby wrapping the inorganic filler / modified thermal insulation filler in the matrix, playing a retention effect, thereby significantly improving the retention rate and stability of the inorganic filler / modified thermal insulation filler. In summary, the inorganic fiber composite thermal insulation material of the present invention has excellent low thermal conductivity, high temperature resistance and strength, and meets the requirements for thermal insulation materials to maintain good thermal insulation performance under harsh environments.

Description

Technical Field

[0001] The invention relates to the field of thermal insulation materials, and in particular to an inorganic fiber composite thermal insulation material and a preparation method thereof. Background Art

[0002] With the development and progress of social science and technology, energy issues have become one of the major problems that hinder social development and need to be solved urgently, and energy conservation has become a topic of increasing concern. To meet this need, the development and application of new refractory insulation materials are imminent. There are many types of insulation materials on the market, and the quantity is huge. In general, with the increase of the use temperature, the types of materials that can be selected are decreasing. Inorganic fiber felts composed of inorganic fibers such as glass wool and rock wool have been widely used in industrial and residential insulation materials and sound-absorbing materials. However, the thermal insulation performance of the fiber cannot meet the requirements under high temperature and other conditions. In order to improve the high-temperature thermal insulation performance of the material, it is necessary to further add inorganic fillers.

[0003] Usually, inorganic fillers are in powder form, which are different from the surface properties and morphology of fibers. There are huge differences in aspects such as surface polarity and surface energy, which leads to weak interaction between the two and poor interface bonding force. Therefore, in the papermaking molding process, the inorganic filler powder retention rate is low, the product strength decreases, and it is easy to lose powder and hair.

[0004] In order to solve the above technical problems, in the field of papermaking, a part of the inorganic filler prepared on site is precipitated in the fiber cell wall and the fiber lumen by using cell filling technology. After papermaking, most of the inorganic fillers are compounded with the fiber. Compared with the traditional direct filling, the retention rate of the inorganic filler is improved and the burden of subsequent water treatment is reduced. However, due to its complex process and high cost, this method is hindered from being used in actual production. At present, the more effective method is to add various retention aids to the slurry, but this method is to flocculate the inorganic filler powder into large particle flocs through charge neutralization so as to be bridged and trapped in the fiber. Since the inorganic filler powder still has no binding force with the fiber, it cannot solve the contradiction between the increase in the amount of inorganic filler powder and the decrease in product strength. Similarly, when preparing inorganic fiber composite insulation materials using papermaking molding technology, similar problems will be encountered. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides an inorganic fiber composite thermal insulation material and a preparation method thereof. The composite thermal insulation material of the present invention contains a polyacrylic acid modified multimetal compound as a modified thermal insulation filler. On the one hand, the mutual doping of multimetal elements in the multimetal compound can reduce the thermal conductivity of the material; on the other hand, during the material molding process, polyacrylic acid can promote the appropriate degree of flocculation of inorganic fibers, thereby wrapping the inorganic filler / modified thermal insulation filler in the matrix, playing a retention effect, thereby significantly improving the retention rate and stability of the inorganic filler / modified thermal insulation filler. In summary, the inorganic fiber composite thermal insulation material of the present invention has excellent low thermal conductivity, high temperature resistance and strength, which meets the requirements of thermal insulation materials to maintain good thermal insulation performance in harsh environments.

[0006] The specific technical scheme of the present invention is:

[0007] In a first aspect, the present invention provides an inorganic fiber composite thermal insulation material, comprising:

[0008] A sheet-like matrix formed by flocculation and entanglement of inorganic fibers;

[0009] The inorganic filler and the modified thermal insulation filler are uniformly dispersed in the matrix; the modified thermal insulation filler is a polyacrylic acid modified multi-metal compound.

[0010] The composite thermal insulation material of the present invention is formed by a papermaking process and is in the form of a sheet. The matrix is ​​inorganic fibers that are flocculated and entangled with each other during the papermaking process. Inorganic fillers and modified thermal insulation fillers are evenly dispersed in the matrix. The modified thermal insulation filler is a polyacrylic acid modified multimetal compound.

[0011] The thermal conductivity of the material is composed of the thermal conductivity of the gas phase and the thermal conductivity of the solid phase, wherein the thermal conductivity of the solid phase is determined by its phonon and electron transport, and the reduction in thermal conductivity is related to the increase in phonon scattering caused by polymetallic ions. In the polyacrylic acid modified polymetallic compound of the present invention, the phonon mean free path of the polymetallic compound is reduced by mutual doping of polymetallic elements, mass scattering and bond disorder are increased, the valence electron coverage space is increased, the solid phase thermal conductivity of the material is reduced, and thus the thermal conductivity of the material is reduced. At the same time, the present invention utilizes the porosity of the material (the matrix has a porous structure), increases the specific surface area of ​​the material, reduces the gas phase thermal conductivity of the material, and further reduces the thermal conductivity of the material. Therefore, the polymetallic compound of the present invention has excellent high temperature resistance after being calcined.

[0012] On the other hand, in order to improve the retention rate of inorganic fillers / modified thermal insulation fillers during the material molding process to improve the thermal insulation, high temperature resistance and strength of the product, the present invention adopts polyacrylic acid grafted modified multi-metal compounds. During the molding process, polyacrylic acid can promote the appropriate degree of flocculation of inorganic fibers, thereby wrapping the inorganic fillers / modified thermal insulation fillers in the matrix, playing a retention effect, strengthening the interfacial interaction between them and the inorganic fibers, and having higher stability.

[0013] In summary, the inorganic fiber composite thermal insulation material of the present invention has excellent low thermal conductivity, high temperature resistance and strength, and meets the requirements for thermal insulation materials to maintain good thermal insulation performance in harsh environments.

[0014] Preferably, the inorganic fiber is one or more of aluminum silicate fiber, alkaline earth silicate fiber, alumina fiber, glass fiber, quartz glass fiber, boron fiber, basalt fiber, silicon carbide fiber, silicon nitride fiber, mullite fiber, boron nitride fiber and nano calcium phosphate fiber, with a diameter of 0.5-10 μm and a length of 0.001-5 cm.

[0015] Preferably, the particle size of the polyacrylic acid modified multimetallic compound is 0.5-20 μm.

[0016] Preferably, the inorganic filler is one or more of unexpanded vermiculite, fumed silica, unexpanded perlite, pumice, diatomaceous earth, titanium dioxide particles and zirconium oxide particles, and the particle size is 0.005-0.8 mm.

[0017] Preferably, the polymetallic compounds in the polyacrylic acid modified polymetallic compound are Zn, Al, Sn and Ti.

[0018] The present invention has found through experiments that the multi-metal compound prepared by selecting the above four metal elements and doping them with each other is particularly effective in reducing the thermal conductivity of the material.

[0019] More preferably, the molar ratio of Zn, Al, Sn and Ti in the polyacrylic acid modified multimetallic compound is 3:0.6-1.0:0.01-0.4:0.01-0.4.

[0020] The present invention finds that the ratio between the above four metal elements has a relatively important influence on the thermal conductivity of the material, especially the ratio of Sn to Ti. It is finally found that when the molar ratio of tin to titanium is about 1:3, the thermal insulation effect is best.

[0021] Preferably, the composite thermal insulation material comprises the following raw materials in parts by weight: 0.5-0.7 parts of inorganic filler, 0.01-0.05 parts of modified starch, 1.0 parts of inorganic fiber, 0.2-0.4 parts of modified thermal insulation filler, 0-0.03 parts of dispersant, 0-0.02 parts of defoaming agent, 0-0.05 parts of adhesive, and 80-120 parts of water.

[0022] Preferably, the inorganic fiber composite thermal insulation material has a low-temperature thermal conductivity of ≤0.013 (W / (m·K) at 25°C, and a high-temperature thermal conductivity of ≤0.060 (W / (m·K) at 1000°C.

[0023] Preferably, the modified starch is selected from one or more of cationic starch, anionic starch and phosphate starch.

[0024] Preferably, the adhesive is selected from one or more of water-based epoxy adhesive, water-based acrylic adhesive, water-based phenolic resin adhesive, water-based polyurethane adhesive and rosin latex.

[0025] Preferably, the dispersant is selected from one or more of fatty alcohol polyoxyethylene ether methyl silane, oleic acid polyoxyethylene ester, fatty alcohol polyoxyethylene ether sodium sulfate, cellulose sodium sulfate, sodium alkyl diphenyl ether sulfonate, alkylphenol polyoxyethylene ether phosphate salt, potassium pyrophosphate, sodium hexametaphosphate, sodium alginate, agar, gum arabic, locust bean gum, gelatin, casein microbial gum guar gum, xanthan gum, carboxymethyl cellulose, methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxypropyl methyl cellulose, hydroxymethyl hydroxyethyl cellulose, cyanoethyl starch, polyacrylamide, polyacrylic acid, polymethacrylic acid, polyvinyl alcohol and polyethylene oxide polyvinyl pyrrolidone.

[0026] Preferably, the defoamer is selected from one or more of mineral oil defoamers, amide defoamers, lower alcohol defoamers, fatty acid and fatty acid ester defoamers, phosphate defoamers, polyether defoamers, silicone defoamers and polyether-modified polysiloxane defoamers.

[0027] In a second aspect, the present invention provides a method for preparing an inorganic fiber composite thermal insulation material, comprising:

[0028] S1: Mix soluble metal salts containing multiple metal elements and dissolve them in water to obtain solution A; dissolve sodium carbonate in water to obtain solution B; add solution B dropwise to solution A, add alkali to adjust the solution pH to 9-10, crystallize, cool, filter, wash, dry, grind, and calcine at 550-650°C for 1.5-2.5h to obtain a multimetallic compound ([M 1-x-y 2+ M x 3+ M y4+ (OH)2] (x+2y)+ (A c- ) (x+2y) / c mH2O, where M 2+ / M 3+ / M 4+ are divalent / trivalent / tetravalent metal cations, respectively, c- is the interlayer anion).

[0029] The present invention finds that the calcination temperature has a great influence on the structure and thermal conductivity of the multimetallic compound. Specifically, as the calcination temperature increases, the specific surface area of ​​the material increases first and then decreases, and the specific surface area of ​​the product calcined at 550-650°C is the largest. This is because too high a calcination temperature will cause the small pores of the material to collapse into large pores, and the average pore size will continue to increase, so the thermal conductivity is larger.

[0030] S2: Mix the polymetallic compound with an alkenyl-containing silane coupling agent solution, stir the resulting suspension for reaction, filter and dry to obtain a silane coupling agent-modified polymetallic compound; add the suspension to an acrylic acid solution for ultrasonic treatment, and then irradiate with a high-energy electron beam in nitrogen. The product is filtered, washed and dried to obtain a polyacrylic acid-modified polymetallic compound with a polyacrylic acid grafting rate of 5.3-5.8wt%.

[0031] The present invention finds that under the condition of fixing the content of polyacrylic acid modified multimetallic compound, the grafting rate of acrylic acid on the surface of the multimetallic compound has a significant effect on the thermal conductivity of the final composite thermal insulation material. Specifically: as the amount of polyacrylic acid or the energy of the electron beam increases, the grafting rate can be increased. However, the present invention finds that the thermal conductivity of the material first increases and then decreases with the increase of the grafting rate of polypropylene. This is because the increase in the grafting rate of polypropylene can increase the retention rate of polyacrylic acid modified multimetallic compound and inorganic filler in the matrix. However, the present invention finds that when the grafting rate of polypropylene is higher, the thermal conductivity will increase due to the excessively high organic content, and the inorganic fibers will also agglomerate due to excessive flocculation, thereby affecting the molding quality of the material (even making it impossible to form a mold).

[0032] S3: Mix water and inorganic filler evenly, add modified starch dropwise while stirring, stir until it becomes flocculent, then add inorganic fiber, modified thermal insulation filler (polyacrylic acid modified multimetallic compound), dispersant, defoamer and adhesive to obtain a mixed slurry; form it through a flat filter screen (remove most of the water under the action of gravity), remove water by negative pressure filtration, and dry to obtain an inorganic fiber composite thermal insulation material.

[0033] Preferably, in S1, the crystallization temperature is 110-130°C and the time is 2-4h.

[0034] Preferably, in S2, the solvent of the alkenyl-containing silane coupling agent solution is 90-98 vol% ethanol aqueous solution, and the concentration of the alkenyl-containing silane coupling agent is 3-7 wt%.

[0035] Preferably, in S2, during the high-energy electron beam irradiation, the energy of the high-energy electron beam is 40-80 kGy, and the amount of acrylic acid used is 25-35 wt % of the multi-metal compound.

[0036] Preferably, in S2, the stirring reaction temperature is 50-70°C and the time is 50-70 min.

[0037] Preferably, in S2, the acrylic acid solution further contains acrylic acid phosphate, and the molar ratio of acrylic acid to acrylic acid phosphate is (3-5):1.

[0038] In order to further enhance the bonding strength between inorganic fiber and modified thermal insulation filler during the papermaking process, an appropriate amount of acrylic acid phosphate can be added to the acrylic acid monomer. After the acrylic acid phosphate participates in the copolymerization, it can significantly enhance the bonding strength between the polymer and the inorganic fiber, thereby enhancing the retention rate of the modified thermal insulation filler in the finished material. Therefore, the same effect can be achieved to a certain extent at a lower consumption of modified thermal insulation filler.

[0039] Preferably, in S3, the stirring rate when adding the modified starch is 100-400 rpm and the time is 10-30 min.

[0040] Compared with the prior art, the beneficial effects of the present invention are:

[0041] (1) The composite thermal insulation material of the present invention contains polyacrylic acid modified multimetallic compounds as modified thermal insulation fillers. On the one hand, the mutual doping of multimetals in the multimetallic compounds can reduce the mean free path of phonons of the multimetallic compounds, increase mass scattering and bond disorder, increase the valence electron coverage space, and reduce the solid phase thermal conductivity of the material, thereby reducing the thermal conductivity of the material; on the other hand, during the material molding process, polyacrylic acid can promote the appropriate degree of flocculation of inorganic fibers, thereby wrapping the inorganic filler / modified thermal insulation filler in the matrix, playing a retention effect, thereby significantly improving the retention rate and stability of the inorganic filler / thermal insulation inorganic filler. In summary, the inorganic fiber composite thermal insulation material of the present invention has excellent low thermal conductivity, high temperature resistance and strength, and meets the requirements of thermal insulation materials to maintain good thermal insulation performance under harsh environments.

[0042] (2) The present invention further improves the thermal insulation effect and mechanical properties of the composite thermal insulation material by optimizing the types / proportions of multiple metals, the roasting process, and the polypropylene modified multiple metal compound process. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1This is a SEM photo (2K times) of the composite thermal insulation material obtained in Test Examples 2-4 of this application;

[0044] Figure 2 This is a SEM photograph (200 times) of the composite thermal insulation material obtained in Test Examples 2-4 of the present application. DETAILED DESCRIPTION

[0045] The present invention will be further described below in conjunction with the embodiments.

[0046] Overall embodiment

[0047] An inorganic fiber composite thermal insulation material comprises: a sheet-like matrix formed by flocculating and entangled inorganic fibers; and inorganic fillers and modified thermal insulation fillers uniformly dispersed in the matrix; the modified thermal insulation fillers are polyacrylic acid modified multimetallic compounds.

[0048] In some specific implementation cases, the composite thermal insulation material includes the following raw materials in parts by weight: 0.5-0.7 parts of inorganic filler, 0.01-0.05 parts of modified starch, 1.0 parts of inorganic fiber, 0.2-0.4 parts of modified thermal insulation filler, 0-0.03 parts of dispersant, 0-0.02 parts of defoaming agent, 0-0.05 parts of adhesive, and 80-120 parts of water.

[0049] In some more specific implementation cases, the polymetallic compounds in the polyacrylic acid modified polymetallic compound are Zn, Al, Sn and Ti; further preferably, the molar ratio of Zn, Al, Sn and Ti in the polyacrylic acid modified polymetallic compound is 3:0.6-1.0:0.01-0.4:0.01-0.4.

[0050] In some more specific implementation cases, the inorganic fiber is one or more of aluminum silicate fiber, alkaline earth silicate fiber, alumina fiber, glass fiber, quartz glass fiber, boron fiber, basalt fiber, silicon carbide fiber, silicon nitride fiber, mullite fiber, boron nitride fiber and nano calcium phosphate fiber, with a diameter of 0.5-10 μm and a length of 0.001-5 cm.

[0051] In some more specific implementation cases, the particle size of the polyacrylic acid modified multi-metal compound is 0.5-20 μm.

[0052] In some more specific implementation cases, the inorganic filler is one or more of unexpanded vermiculite, fumed silica, unexpanded perlite, pumice, diatomaceous earth, titanium dioxide particles and zirconium oxide particles, and the particle size is 0.005-0.8 mm.

[0053] In some more specific implementation cases, the modified starch is selected from one or more of cationic starch, anionic starch and phosphate starch.

[0054] In some more specific implementation cases, the adhesive is selected from one or more of water-based epoxy adhesive, water-based acrylic adhesive, water-based phenolic resin adhesive, water-based polyurethane adhesive and rosin latex.

[0055] In some more specific implementation cases, the dispersant is selected from one or more of fatty alcohol polyoxyethylene ether methyl silane, oleic acid polyoxyethylene ester, fatty alcohol polyoxyethylene ether sodium sulfate, cellulose sodium sulfate, alkyl diphenyl ether sodium sulfonate, alkylphenol polyoxyethylene ether phosphate salt, potassium pyrophosphate, sodium hexametaphosphate, sodium alginate, agar, gum arabic, locust bean gum, gelatin, casein microbial gum guar gum, xanthan gum, carboxymethyl cellulose, methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxypropyl methyl cellulose, hydroxymethyl hydroxyethyl cellulose, cyanoethyl starch, polyacrylamide, polyacrylic acid, polymethacrylic acid, polyvinyl alcohol and polyethylene oxide polyvinyl pyrrolidone.

[0056] In some more specific implementation cases, the defoamer is selected from one or more of mineral oil defoamers, amide defoamers, lower alcohol defoamers, fatty acids and fatty acid ester defoamers, phosphate defoamers, polyether defoamers, silicone defoamers and polyether-modified polysiloxane defoamers.

[0057] A method for preparing an inorganic fiber composite thermal insulation material, comprising:

[0058] S1: Mix soluble metal salts containing multiple metal elements and dissolve them in water to obtain solution A; dissolve sodium carbonate in water to obtain solution B; add solution B dropwise into solution A, add alkali to adjust the solution pH to 9-10, perform crystallization reaction, cool, filter, wash, dry, grind, and roast at 550-650°C for 1.5-2.5h to obtain a multi-metal compound.

[0059] In some more specific implementation cases, in S1, the crystallization temperature is 110-130° C. and the time is 2-4 hours.

[0060] S2: Mix the polymetallic compound with an alkenyl-containing silane coupling agent solution, stir the resulting suspension for reaction, filter and dry to obtain a silane coupling agent-modified polymetallic compound; add the suspension to an acrylic acid solution for ultrasonic treatment, and then irradiate with a high-energy electron beam in nitrogen. The product is filtered, washed and dried to obtain a polyacrylic acid-modified polymetallic compound with a polyacrylic acid grafting rate of 5.3-5.8wt%.

[0061] In some more specific implementation cases, in S2, the solvent of the alkenyl-containing silane coupling agent solution is 90-98 vol% ethanol aqueous solution, and the concentration of the alkenyl-containing silane coupling agent is 3-7 wt%.

[0062] In some more specific implementation cases, in S2, during the high-energy electron beam irradiation, the energy of the high-energy electron beam is 40-80 kGy, and the amount of acrylic acid used is 25-35 wt % of the multi-metal compound.

[0063] In some more specific implementation cases, in S2, the acrylic acid solution further contains acrylic acid phosphate, and the molar ratio of acrylic acid to acrylic acid phosphate is (3-5):1.

[0064] In some more specific implementation cases, in S2, the stirring reaction temperature is 50-70°C and the time is 50-70 min.

[0065] S3: Mix water and inorganic filler evenly, add modified starch dropwise while stirring, stir until it becomes flocculent, then add inorganic fiber, modified thermal insulation filler, dispersant, defoamer and adhesive to obtain a mixed slurry; form it through a flat filter screen (remove most of the water under the action of gravity), remove water by negative pressure filtration, and dry it to obtain an inorganic fiber composite thermal insulation material.

[0066] In some more specific implementation cases, in S3, the stirring rate when adding the modified starch is 100-400 rpm, and the time is 10-30 min.

[0067] Specific Examples and Comparative Examples (I) Effects of Different Metal Element Ratios and Calcination Temperatures on the Properties of Composite Insulation Materials

[0068] 1) Press n(Zn 2+ )∶n(M 3+ / 4+ )=3∶1(Zn 2+ The concentration is 3 mol / L, M 3+ / 4+ For Al 3+ Sn 4+ 、Ti 4+ The total concentration is 1 mol / L), soluble metal salts of zinc nitrate hexahydrate, aluminum nitrate nonahydrate, tin chloride pentahydrate and titanium tetrachloride are mixed and dissolved in 500 mL of deionized water to obtain solution A; according to n(CO3 2- )∶n(N 2+ / 3+ / 4+ )(N 2+ / 3+ / 4+ Zn 2+ 、Al 3+ Sn 4+ 、Ti 4+ Sodium carbonate was dissolved in 500 mL of deionized water to obtain solution B.

[0069] 2) Solution B is slowly added dropwise to solution A, followed by adding 1 mol / L sodium hydroxide solution to adjust the pH value of the solution to 9, and the mixed solution is transferred to a reactor lined with polytetrafluoroethylene, and placed in an oven. After constant temperature crystallization at 120°C for 3 hours, the reactor is taken out and cooled to room temperature. After filtering, the filter cake is washed with water until the filtrate is neutral, dried and ground, and calcined at 400-700°C for 2 hours to obtain a multimetallic compound.

[0070] 3) The polymetallic compound and 0.4 wt% of γ-methacryloxypropyltrimethoxysilane in 95 vol% ethanol aqueous solution were prepared into a 5 wt% suspension, mechanically stirred for reaction at 60°C for 60 min, filtered and dried to obtain a silane coupling agent modified polymetallic compound. 1 part by weight of the silane coupling agent modified polymetallic compound was added to 50 parts by weight of 0.5 wt% acrylic acid / ethanol solution for ultrasonic treatment, and the mixture was irradiated with a high-energy electron beam energy of 60 kGy in nitrogen, the product was filtered and washed with ethanol, and then dried at high temperature in vacuum to obtain a polyacrylic acid modified polymetallic compound with a particle size of 5-10 μm.

[0071] 4) 100 parts by weight of water and 0.6 parts by weight of diatomaceous earth (diameter 60-150 μm) were stirred at 250 rpm for 20 min, and 0.03 parts by weight of phosphate starch was added dropwise while stirring, and the starch was slowly stirred until the starch was flocculent; then 1.0 parts by weight of alkaline earth silicate fiber (diameter 3-4 μm, length 0.5-1 cm), 0.3 parts by weight of modified thermal insulation filler, 0.03 parts by weight of polyvinyl alcohol, 0.02 parts by weight of polyether defoamer (Hongtai X-2415) and 0.05 parts by weight of water-based epoxy resin adhesive (Hunsman's PZ 3901 and 435 (mass ratio 1:1)) to obtain a mixed slurry. The mixed slurry is formed by passing through a flat filter screen (most of the water is removed under the action of gravity), and then filtered under negative pressure to remove water to obtain a composite sheet, which is then dried to obtain a composite thermal insulation material (about 1.2 mm thick).

[0072] Performance comparison

[0073] Table 1: Effects of different M metal element ratios and calcination temperatures on the performance of composite insulation materials

[0074]

[0075]

[0076] From the data in the above table, we can see that:

[0077] In test examples 1-1 to 1-5, with other conditions unchanged, Sn 4+ The content of Al 3+The results show that the specific surface area of ​​the composite thermal insulation material also increases, and the thermal conductivity at room temperature (25°C) decreases slightly. Relatively speaking, the thermal conductivity at high temperature (1000°C) decreases more significantly, which shows that with the increase of Sn 4+ The gradual increase in content mainly improves the high-temperature thermal insulation properties of the composite thermal insulation material.

[0078] In test examples 1-6 to 1-9, when other conditions remain unchanged, Ti 4+ The content of Al 3+ The content of Ti decreases relatively), which is similar to that in Test Examples 1-1 to 1-5. The results show that the specific surface area of ​​the obtained composite thermal insulation material increases gradually, and the thermal conductivity at room temperature (25°C) also decreases slightly. Relatively speaking, the decrease in the thermal conductivity of the composite thermal insulation material at high temperature (1000°C) is more significant, which shows that with the increase of Ti 4+ The gradual increase in content mainly improves the high-temperature thermal insulation properties of the composite thermal insulation material.

[0079] In test examples 1-10 to 1-15, the 4+ and Ti 4+ The results show that the composite of multiple tetravalent metals has a more significant improvement on the thermal insulation performance of composite thermal insulation materials than a single tetravalent metal. 4+ and Ti 4+ When the molar ratio of is 1:3, the specific surface area, room temperature thermal conductivity and high temperature thermal conductivity of the obtained composite thermal insulation material are optimal. Therefore, the comprehensive thermal insulation performance of the composite thermal insulation material obtained in Test Examples 1-13 is the best.

[0080] Test Examples 1-13, 1-16 to 1-18 studied the effects of different calcination temperatures on the performance of composite thermal insulation materials. The results show that with the increase of the calcination temperature, the specific surface area first increases and then decreases. Among them, the composite thermal insulation material calcined at 600°C has the largest specific surface area and the largest number of small pores. At the same time, the room temperature thermal conductivity and high temperature thermal conductivity of the obtained composite thermal insulation material are also the lowest. However, when the calcination temperature reaches or exceeds 700°C, the specific surface area begins to decline, and the room temperature thermal conductivity and high temperature thermal conductivity also begin to rise. This is because the higher calcination temperature will cause the small pores of the polymetallic compound to collapse to form large pores, and the average pore size continues to increase (especially the room temperature thermal conductivity increases more, even higher than Test Example 1-1).

[0081] (II) Effect of polyacrylic acid grafting rate on the performance of composite insulation materials

[0082] 1) Press n(Zn 2+)∶n(M 3+ / 4+ )=3∶1 molar ratio(Zn 2+ concentration of 3 mol / L) and n(Al 3+ )∶n(Sn 4+ )∶n(Ti 4 + )=0.6∶0.1∶0.3 molar ratio, zinc nitrate hexahydrate, aluminum nitrate nonahydrate, tin chloride pentahydrate and titanium tetrachloride were mixed and dissolved in 500 mL of deionized water to obtain solution A; according to n(CO3 2- )∶n(N 2+ / 3+ / 4+ )=5:4 Sodium carbonate was dissolved in 500 mL of deionized water to obtain solution B.

[0083] 2) Solution B is slowly added dropwise to solution A, and then 1 mol / L sodium hydroxide solution is added dropwise to adjust the pH value of the solution to 9. The mixed solution is transferred to a reactor lined with polytetrafluoroethylene, placed in an oven, and crystallized at a constant temperature of 120°C for 3 hours. The reactor is then taken out and cooled to room temperature. After filtering, the filter cake is washed with water until the filtrate is neutral, dried and ground, and calcined at 600°C for 2 hours to obtain a polymetallic compound.

[0084] 3) The polymetallic compound and 0.4 wt% of γ-methacryloxypropyltrimethoxysilane in 95 vol% ethanol aqueous solution are prepared into a 5 wt% suspension, the suspension is reacted at 60°C with mechanical stirring for 60 min, and the suspension is filtered and dried to obtain a silane coupling agent modified polymetallic compound. 1-5 parts by weight of the silane coupling agent modified polymetallic compound is added to 50 parts by weight of an acrylic acid / ethanol solution with a concentration of 0.5-2 wt% and subjected to ultrasonic treatment, and the mixture is irradiated with a high-energy electron beam energy of 40-80 kGy in nitrogen, the product is filtered and washed with ethanol, and then dried at high temperature in vacuum to obtain polyacrylic acid modified polymetallic compounds with different polyacrylic acid grafting rates.

[0085] 4) 100 parts by weight of water and 0.6 parts by weight of diatomaceous earth (diameter 60-150 μm) were mixed and stirred at 250 rpm for 20 min, and 0.03 parts by weight of phosphate starch was added dropwise while stirring, and the starch was slowly stirred until it was flocculent; then 1.0 parts by weight of alkaline earth aluminum silicate fiber (diameter 3-4 μm, length 0.5-1 cm), 0.3 parts by weight of modified thermal insulation filler, 0.03 parts by weight of polyvinyl alcohol, 0.02 parts by weight of polyether defoamer (Hongtai X-2415) and 0.05 parts by weight of water-based epoxy resin adhesive (Hunsman's PZ 3901 and 435 (mass ratio 1:1)) agent to obtain a mixed slurry. The mixed slurry is passed through a flat filter screen to form a sheet (most of the water is removed under gravity), and then filtered under negative pressure to remove water to obtain a composite sheet, which is then dried to obtain a composite thermal insulation material (about 1.2 mm thick).

[0086] Table 2: Effect of polyacrylic acid grafting amount on the performance of composite insulation materials

[0087]

[0088]

[0089] Note: The grafting rate (polyacrylic acid) is determined by the thermal gravimetric method, which measures the difference in mass of the multimetallic compound before and after modification at 150°C and 600°C; the ratio of this mass difference to the mass of the multimetallic compound before modification at 600°C is the grafting rate. The retention rate (inorganic filler / thermal insulation filler) is the ratio of the mass of the composite thermal insulation material obtained after drying to the absolute dry amount of the raw materials added to the slurry.

[0090] From the results in the above table, we can see that:

[0091] In Test Examples 2-1 to 2-3, the effects of different ratios of modified multimetallic compounds and acrylic acid on the grafting rate of polyacrylic acid on the modified multimetallic compounds and the various properties of the resulting composite thermal insulation materials were studied under the condition of an electron beam energy of 40 kGy. The results show that as the ratio of modified multimetallic compounds to acrylic acid decreases, the grafting rate of polyacrylic acid on the modified multimetallic compounds gradually increases, and at the same time, the retention rate of inorganic fillers / thermal insulation functional fillers in the resulting composite thermal insulation materials also gradually increases. This is because the higher content of polyacrylic acid on the surface of the modified multimetallic compound gradually enhances the flocculation effect on inorganic fibers, thereby improving the adhesion ability to inorganic fillers / thermal insulation functional fillers. In terms of thermal insulation performance, as the grafting rate increases, the room temperature thermal conductivity of the resulting composite thermal insulation material decreases slightly, while the decrease in high temperature thermal conductivity is more obvious. In terms of mechanics, the pre-tensile strength of the resulting composite thermal insulation material gradually increases.

[0092] Test Examples 2-4 to 2-6 studied the effects of different ratios of modified multimetallic compounds to acrylic acid on the grafting rate of polyacrylic acid on the modified multimetallic compounds and the various properties of the resulting composite thermal insulation materials under the condition of an electron beam energy of 60 kGy. The results were consistent with those of Test Examples 2-1 to 2-3. In addition, Figure 1 and 2 All are SEM photos of the composite thermal insulation materials obtained in Test Examples 2-4 of this application. Figure 1 The photo shows that a large amount of polyacrylic acid remains on the surface of the inorganic fibers in the obtained composite thermal insulation material to modify the multi-metal compound, and the inorganic fibers are in a highly cross-linked state ( Figure 2 ).

[0093] In test examples 2-7 to 2-9, the effects of different ratios of modified multimetallic compounds and acrylic acid on the grafting rate of polyacrylic acid on the modified multimetallic compounds and the various properties of the resulting composite thermal insulation materials were studied under the condition of an electron beam energy of 80 kGy. The results showed that when the grafting rate of polyacrylic acid was greater than or equal to 5.9%, the metal compounds were more likely to agglomerate due to the increase in the amount of modification, resulting in a decrease in the retention rate and a beginning increase in the thermal conductivity.

[0094] By comparing the above three test cases, it can be found that with the increase of electron beam energy, the grafting rate of polyacrylic acid increases, and the high-temperature thermal conductivity increases first and then decreases with the increase of grafting rate. This is because the increase of grafting rate can improve the retention rate of inorganic fillers / insulating functional fillers, but the thermal insulation performance will be reduced due to the increase of organic matter content. In general, when the grafting rate of polyacrylic acid is 5.3-5.8wt%, the comprehensive performance of the obtained composite thermal insulation material is better.

[0095] (III) Effect of acrylic monomer type on the performance of composite insulation materials

[0096] 1) Press n(Zn 2+ )∶n(M 3+ / 4+ )=3∶1 molar ratio(Zn 2+ concentration of 3 mol / L) and n(Al 3+ )∶n(Sn 4+ )∶n(Ti 4 + )=0.6∶0.1∶0.3 molar ratio, zinc nitrate hexahydrate, aluminum nitrate nonahydrate, tin chloride pentahydrate and titanium tetrachloride were mixed and dissolved in 500 mL of deionized water to obtain solution A; according to n(CO3 2- )∶n(N 2+ / 3+ / 4+ )=5:4 Sodium carbonate was dissolved in 500 mL of deionized water to obtain solution B.

[0097] 2) Solution B is slowly added dropwise to solution A, and then 1 mol / L sodium hydroxide solution is added dropwise to adjust the pH value of the solution to 9. The mixed solution is transferred to a reactor lined with polytetrafluoroethylene, placed in an oven, and crystallized at a constant temperature of 120°C for 3 hours. The reactor is then taken out and cooled to room temperature. After filtering, the filter cake is washed with water until the filtrate is neutral, dried and ground, and calcined at 600°C for 2 hours to obtain a polymetallic compound.

[0098] 3) The polymetallic compound and 0.4 wt% of γ-methacryloxypropyltrimethoxysilane in 95 vol% ethanol aqueous solution were prepared into a 5 wt% suspension, mechanically stirred for reaction at 60°C for 60 min, filtered and dried to obtain the silane coupling agent modified polymetallic compound. 1 part by weight of the silane coupling agent modified polymetallic compound was added to 50 parts by weight of 0.5 wt% acrylic monomer / ethanol solution for ultrasonic treatment, and the mixture was irradiated with a high-energy electron beam energy of 60 kGy in nitrogen, the product was filtered and washed with ethanol, and then dried at high temperature in vacuum to obtain polyacrylic acid modified polymetallic compounds with different polyacrylic acid grafting rates.

[0099] 4) 100 parts by weight of water and 0.6 parts by weight of diatomaceous earth (diameter 60-150 μm) were mixed and stirred at 250 rpm for 20 min, and 0.03 parts by weight of phosphate starch was added dropwise while stirring, and the starch was slowly stirred until it was flocculent; then 1.0 parts by weight of alkaline earth aluminum silicate fiber (diameter 3-4 μm, length 0.5-1 cm), 0.3 parts by weight of modified thermal insulation filler, 0.02 parts by weight of polyether defoamer (Hongtai X-2415) and 0.05 parts by weight of water-based epoxy resin adhesive (Hunsman's PZ 3901 and 435 (mass ratio 1:1)) to obtain a mixed slurry. The mixed slurry is formed by passing through a flat filter screen (most of the water is removed under the action of gravity), and then filtered under negative pressure to remove water to obtain a composite sheet, which is then dried to obtain a composite thermal insulation material (about 1.2 mm thick).

[0100] Table 3: Effect of acrylic monomer type on the performance of composite insulation materials

[0101]

[0102] From the results in the above table, we can see that:

[0103] The difference between Test Example 3-2 and Test Example 3-1 is that the pure acrylic acid monomer is replaced with a mixed monomer of acrylic acid and acrylic acid phosphate at a molar ratio of 3:1 (the total amount remains unchanged). The present invention finds that after an appropriate amount of acrylic acid phosphate is doped in the acrylic acid monomer, the acrylic acid phosphate can participate in the copolymerization of acrylic acid and can improve the bonding force between the polymer and the inorganic fiber, thereby improving the retention rate of the modified thermal insulation filler in the finished material. Therefore, the same thermal insulation effect can be achieved at a lower consumption of the modified thermal insulation filler to a certain extent.

[0104] The raw materials and equipment used in the present invention, unless otherwise specified, are all commonly used raw materials and equipment in the art; the methods used in the present invention, unless otherwise specified, are all conventional methods in the art.

[0105] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent transformation made to the above embodiment based on the technical essence of the present invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. An inorganic fiber composite thermal insulation material, characterized in that include: A sheet-like matrix formed by flocculation and entanglement of inorganic fibers; Inorganic fillers and modified thermal insulation fillers uniformly dispersed in the matrix; The modified heat-insulating filler is a polyacrylic acid-modified multimetal compound with a polyacrylic acid grafting rate of 5.3-5.8wt%, which is obtained by mixing and stirring the multimetal compound with a silane coupling agent solution containing an alkenyl group, filtering and drying, adding it to an acrylic acid solution for ultrasonic treatment, irradiating it with a high-energy electron beam in an inert atmosphere, filtering, washing, and drying; the chemical formula of the multimetal compound is [M 1-x-y 2+ M x 3+ M y 4+ (OH)2] (x+2y)+ (A c- ) (x+2y) / c mH2O, where M 2+ / M 3+ / M 4+ are divalent / trivalent / tetravalent metal cations, respectively, c- It is the interlayer anion; the metal cation elements are Zn, Al, Sn and Ti.

2. The composite thermal insulation material according to claim 1, characterized in that: The inorganic fiber is one or more of aluminum silicate fiber, alkaline earth silicate fiber, alumina fiber, glass fiber, boron fiber, basalt fiber, silicon carbide fiber, silicon nitride fiber, mullite fiber, boron nitride fiber and nano calcium phosphate fiber, with a diameter of 0.5-10 μm and a length of 0.001-5 cm; The particle size of the polyacrylic acid modified multimetallic compound is 0.5-20 μm; The inorganic filler is one or more of unexpanded vermiculite, fumed silica, unexpanded perlite, pumice, diatomaceous earth, titanium dioxide particles and zirconium oxide particles, and the particle size is 0.005-0.8 mm.

3. The composite thermal insulation material according to claim 1, characterized in that: The molar ratio of Zn, Al, Sn and Ti in the polyacrylic acid modified multimetallic compound is 3:0.6-1.0:0.01-0.2:0.01-0.

2.

4. The composite thermal insulation material according to any one of claims 1 to 3, characterized in that: The invention comprises the following raw materials in parts by weight: 0.5-0.7 parts of inorganic filler, 0.01-0.05 parts of modified starch, 1.0 parts of inorganic fiber, 0.2-0.4 parts of modified heat-insulating filler, 0-0.03 parts of dispersant, 0-0.02 parts of defoamer, 0-0.05 parts of adhesive and 80-120 parts of water.

5. The composite thermal insulation material according to claim 1, characterized in that: The low-temperature thermal conductivity of the inorganic fiber composite thermal insulation material at 25°C is ≤0.013 (W / (m·K), and the high-temperature thermal conductivity at 1000°C is ≤0.060 (W / (m·K).

6. A method for preparing the inorganic fiber composite thermal insulation material according to any one of claims 1 to 5, characterized in that include: S1: Mixing and dissolving soluble metal salts containing multiple metal elements in water to obtain solution A; Dissolve sodium carbonate in water to obtain solution B; Add solution B dropwise to solution A, add alkali to adjust the solution pH to 9-10, perform crystallization reaction, cool, filter, wash, dry, grind, and calcine at 550-650° C. for 1.5-2.5 h to obtain a multimetallic compound; S2: mixing the polymetallic compound with a solution of an alkenyl-containing silane coupling agent, stirring the obtained suspension for reaction, filtering and drying, and obtaining a silane coupling agent-modified polymetallic compound; The product is added to an acrylic acid solution for ultrasonic treatment, and then irradiated with a high-energy electron beam in an inert atmosphere. The product is filtered, washed, and dried to obtain a polyacrylic acid-modified multimetallic compound with a polyacrylic acid grafting rate of 5.3-5.8 wt %; S3: Mix water and inorganic filler evenly, add modified starch dropwise while stirring, stir until it becomes flocculent, add inorganic fiber, modified thermal insulation filler, dispersant, defoamer and adhesive to obtain a mixed slurry; shape it through a flat filter screen, remove water by negative pressure filtration, and dry it to obtain an inorganic fiber composite thermal insulation material.

7. The preparation method according to claim 6, characterized in that: In S1, the crystallization temperature is 110-130°C and the time is 2-4h.

8. The preparation method according to claim 6, characterized in that: In S2, the solvent of the alkenyl-containing silane coupling agent solution is 90-98 vol% ethanol aqueous solution, and the concentration of the alkenyl-containing silane coupling agent is 3-7 wt%; During the high-energy electron beam irradiation, the energy of the high-energy electron beam is 40-80 kGy, and the amount of acrylic acid used is 25-35 wt % of the multi-metal compound; The stirring reaction temperature is 50-70°C and the time is 50-70 minutes.

9. The preparation method according to claim 6, characterized in that: In S2, the acrylic acid solution also contains acrylic acid phosphate, and the molar ratio of acrylic acid to acrylic acid phosphate is (3-5):1.

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